This invention relates to a control system for a head restraint adjustably mounted on an automotive seat with the provision of a load-sensitive switch in the seat and a reversible motor responsive to the action of the load-sensitive switch.
The provision of a head restraint on the seat back of an automotive seat is effective for protecting the passenger in the seat against a whiplash injury in case of a rear-end collision of the car. A primitive head restraint is mounted on the seat back so as to rest in a fixed position. When an automotive seat provided with this type of head restraint is left unoccupied while an adjacent seat is occupied by a driver, the head restraint on the unoccupied seat offers considerably and unnecessary obstruction to the side and rear visibility of the driver. If a passenger is seated in a seat behind the unoccupied seat the front visibility of this passenger is greatly and unnecessarily obstructed by the head restraint on the unoccupied seat.
An automatic head restraint adjustment system has been developed to resolve inconveniences of the fixed head restraint. In this case a head restraint is supported by pillars which can be moved in the seat back selectively upwards and downwards by means of a reversible motor and a link mechanism. A control circuit for the control of the operation of the motor includes a load-sensitive switch installed in the seat cushion. The head restraint rests in its lowest position, i.e. on the top of the seat back while the seat is unoccupied. Upon occupation of the seat by a passenger, the head restraint is automatically lifted to take a predetermined position. This position is the highest position the head restraint can take. The adjustment system includes a manually operated selector switch which allows the passenger in the seat to lower and the head restraint from the highest position to an intermediate position suited to the sitting height of the passenger. Irrespective of the ultimately adjusted position, the head restraint is automatically returned to its lowest position in response to withdrawal of the passenger from the seat.
In this system the highest position of the head restraint, i.e. the position preset as the terminal point of the automatic ascent, must be high enough to afford effective protection even to very tall passengers. Accordingly most of the car users need to manually lower the head restraint after completion of its automatic ascent. This means a considerable reduction of the merit of the automatic head restraint adjustment system. To most users this system does not appreciably differ from a more simple system, a manual head restraint adjustment system. The necessity of manual readjustment for most users will be lessened by the employment of a relatively low position as the terminal point of the automatic ascent of the head restraint, i.e. the highest position the head restraint can take. However, such a way of design will result in that the head restraint does not afford sufficient safety to passengers of more than average sitting height.